County routes or highways may or may not be shielded. These roads nearly always carry a local primary street name. CH- designations apply to alternate names almost exclusively. The designation is used to identify county routes for proper application of [[Road types/USA|road types]].
Proper sourcing of county routes and highways is important. The interactive IDOT functional classification map uses a third-party base map source which may not be correct. In order of preference, source county route/highway numbering from WME SV images less than three years old, published county information, or the IDOT county highway maps available at [http://www.idot.illinois.gov/transportation-system/Network-Overview/highway-system/maps
| IDOT Maps.]
''The naming of county highways was changed in July 2016. Previously, county routes were also labeled "CR-" and should be updated to the new guidance. Care must be taken to not change the naming of county/township roads which are currently named using "CR-." See the state to-do list for counties outstanding.''